Integrated circuits with high voltage capabilities have wide industrial applications, including power management systems for use in automobiles. These integrated circuits include high voltage transistors that operate at a high voltage range (e.g., 80v to 120v) and low voltage transistors that operate at a much lower voltage range (e.g., 1v to 5v). To protect the low voltage transistors from the high voltage operations, an integrated circuit may adopt one or more isolation schemes. For instance, one scheme involves forming a buried layer (e.g., an N-type buried layer) on top of a bulk substrate (e.g., a P-type substrate) to isolate the high voltage transistors from the low voltage transistors. The buried layer is typically biased at a high voltage corresponding to the operating range of the high voltage transistors, whereas the bulk substrate is typically biased at a ground supply voltage. In some cases, the difference between the high bias voltage and the ground supply voltage may exceed a breakdown voltage threshold of a PN junction between the buried layer and the bulk substrate, thereby causing leakages and impacting the performance and reliability of the integrated circuit.